Conventionally, a side reinforcing type run flat tire has been proposed (see, for example, Japanese Unexamined Patent Application Publication Nos. H07-304312A and 2009-61866A) as a run flat tire that can travel while flat that has a side reinforcing layer with a falcated cross-section arranged on the inner side of the side wall portion.
With this type of side reinforcing type run flat tire, it is common that the thickness of the side reinforcing layer is greater and a rubber composition having a high hardness is used in the side reinforcing layer in order to increase the durability during run flat traveling.
However, when increasing the thickness of the side reinforcing layer and increasing the hardness of the rubber composition that composes the side reinforcing layer, there is a problem in that the ride comfort degrades during regular traveling in conjunction with the increase in stiffness of the side wall portion, or there is a pronounced increase in the weight of the tire. Therefore, a way is sought to enhance durability during run flat traveling without degrading ride comfort and without increasing the tire weight.